The teen-age boys know they are lucky because they are busy. And they let visitors know it with barely polite answers to questions interrupting their lessons.

Their determination amid the torpor of a 105-degree Sudanese summer is born of desperation. For as the first 95 students culled from Khartoum's population of floating street children, estimated to be between 6,000 and 10,000, they realize their presence at a special vocational school is nothing short of miraculous.

Their performance will determine the future of the project, which began in mid-May at the Belgian-Sudanese Vocational School here. The goal is to turn out badly-needed trained artisans specializing in carpentry, electricity or metalworking and to set them up in business for themselves either in their native regions or in Khartoum, if returning home proves impractical.

The initial nine-month project costs about $45,000 and is financed by UNICEF, the European Community and Band Aid, a private relief organization.

The project is the brainchild of Peter Dalglish, a 29-year-old Nova Scotia lawyer who worked with street children in San Francisco while an undergraduate at Stanford University. Dalglish, who is UNICEF's emergency operations officer here, spent part of last year in the westernmost province of Kordofan, where drought and famine drove many Sudanese from their homes.

Some street kids -- all of whom are boys -- rode the rails on the chaotic, sometimes week-long train from the west to Khartoum, the capital, often climbing through open car windows onto the roof to escape ticket collectors.

Others hitched rides on trucks from the south, fleeing conscription into government or rebel ranks in a civil war that began in 1983. Still others fled home to get away from their parents.

Over the past 18 months of famine and disorder, the boys were drawn to the capital in search of food and employment. It is the first time Khartoum has played host to so many uprooted youngsters.

Most sleep in the streets, especially in and around the central market. One of their favorite spots is close to the nearby police station where friendly policemen protect them from marauding older youths.

A Swedish study showed that their median age is 11 and that they tend to be the oldest boy in the family. Like street kids elsewhere, they begged, robbed and prostituted themselves to keep alive, sniffing glue and gasoline to relieve their boredom and anxiety.

Dalglish convinced Luc de Groote, the director of the Belgian-Sudanese Vocational School, a lavishly endowed schoolroom and workshop complex, to allow the boys to use the premises during the mid-May to mid-July summer holidays.

De Groote designed a special simplified syllabus for the street children, many of whom are illiterate. Thirty-five younger street children are being taught basic Arabic and mathematics on the theory that they will need to read and write to keep simple books when they are in business.

Sixty older boys are brushing up on what they learned in school while specializing in technical courses purposely kept simple. The graduates are supposed to be headed back to the bush, where sophisticated lathes and metal other than used car and truck springs are the exception.

Central to the project is the determination to avoid pampering the students, since it was their survival instincts and self-sufficiency that won them admission to the project in the first place.

De Groote said it took the street children only a few days to get over their initial nervousness -- reflecting a fear of failure -- before they settled down.

Dalglish noted that two days after the program started, the first batch of students complained that the "new" street boys stank and marched them off to the showers.

The students are provided with one hot meal a day. Some go without even rudimentary sandals. The older boys live in tents while building brick housing. The younger students live with Khartoum families.

When the younger students have completed their course, the project will pay for six-month apprenticeships to get them started in business. The older boys will be given tool kits and start-up money to strike out on their own.

Over the years, so many skilled workers have left Sudan for better paying jobs in the Persian Gulf or Libya that the project directors are convinced that the street children will find work easily.

De Groote said he is amazed at the street childrens' progress, which he attributes as much to their thirst for knowledge as to the specially designed small classes where one teacher, one assistant teacher and another assistant provide direct guidance for 15 students.

Teachers said that the street children were learning in 10 hours what it took the vocational school's normal students 25 hours to absorb.

Although some businessmen are wary of taking a chance with street boys because of their unsavory reputation, a leading Sudanese industrialist, Youssef Zaki Sid Ahmad, has backed the project wholeheartedly and is committed to finding jobs for graduates.

Hamad Ahmad Abdulrahman, at age 12 the star pupil in the younger students' Arabic class, hopes soon to know enough to write his first letter home. "Before I could do nothing, I was useless and aimless," he said. "I am very lucky."

Mindful of many other African projects that have died for lack of follow-through, Dalglish said, "We know that nine-tenths of the job is still ahead of us."